JP2003529665A - Method for softening Fischer-Tropsch wax by mild hydrotreatment - Google Patents

Abstract

SUMMARY A novel method for forming a hydrocarbon wax from synthesis gas is disclosed. The present invention adjusts the softness of the wax, as defined by the penetration of the wax according to the ASTM Standard Test Method (ASTM D-1321), into the most preferred area for end-use applications, while at the same time undesired impurities such as It teaches a process in which Fischer-Tropsch wax can be formulated to remove oxygenates (eg, primary alcohols), olefins and trace levels of aromatics, and the like. In a Fischer-Tropsch reactor, Fischer-Tropsch wax is formed from synthesis gas in a catalytic reaction. The Fischer-Tropsch wax is then converted such that essentially no boiling point conversion is obtained, but chemical conversion (e.g., hydrogenation and mild isomerization) occurs, resulting in a high purity hydrocarbon wax product with reduced hardness. Under conditions, it is subjected to a relatively mild hydrotreatment over a hydroisomerization catalyst.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to the production and processing of higher hydrocarbons, especially waxes, which are useful in a wide range of applications where high purity waxes are needed, including coating materials and candles, as well as food and chemicals. Regarding More particularly, the present invention relates to the reaction of carbon monoxide and hydrogen, a highly paraffin wax product produced by the Fischer-Tropsch process. More specifically, the present invention relates to a catalytic process in which a Fischer-Tropsch feedstock wax is subjected to mild isomerization to produce a high purity hydrocarbon wax product that has the desired hardness and does not require further processing. .

BACKGROUND OF THE INVENTION Syngas, commonly known as the Fischer-Tropsch process,
For example, the catalytic production of higher hydrocarbon materials from carbon monoxide and hydrogen has long been known. Such processes rely on specialized catalysts.

The original Fischer-Tropsch synthesis catalyst is typically a Group VIII metal,
Cobalt and iron, in particular, have been used for many years in process-compatible production of higher hydrocarbons. As the technology evolved, these catalysts became more sophisticated, with the addition of other metals that act to promote catalytic activity. Such promoter metals include VIII such as platinum, palladium, ruthenium and iridium.
Group metals and other transition metals such as rhenium and hafnium, and alkali metals. The choice of a particular metal or alloy for making the catalyst used in the Fischer-Tropsch synthesis depends largely on the desired product.

The products from hydrocarbon synthesis must be useful in a variety of applications. The waxy products in hydrocarbon synthesis, especially those from cobalt-based catalytic processes, contain a high proportion of normal paraffins. Paraffin wax obtained from the Fischer-Tropsch process is catalytically converted mainly by hydrotreating, for example, hydrotreating, hydroisomerization and hydrocracking, and low boiling paraffins included in the range of boiling points of gasoline and middle distillates. It is generally known to use organic hydrocarbons. However, new markets for petroleum and synthetic waxes continue to grow. Due to the wide variety and widespread uses of wax in food containers, wax paper, coating materials, electrical insulators, candles, crayons, markers, cosmetics, etc., this material is a by-product class for many applications. Have been promoted to the product class.

[0005] Regulatory authorities such as the US FDA and the European Community SCF have set stringent requirements to which waxes must meet, especially when used in food and pharmaceutical applications. Further, meeting these requirements is a severe challenge for crude oil refiners. Petroleum waxes derived from crude oils are often dark-colored, odorless, contain a large number of impurities and require considerable refining to further satisfy regulatory authorities, especially when used in food and pharmaceutical applications. It needs to be highly purified. The presence of sulfur, nitrogen and aromatic species that color the wax yellow or brown is undesirable in that there is a considerable health risk. Advanced wax refining techniques are required to improve the heat and light properties, UV stability, color, storage stability and oxidation resistance of the final product. Typically, such waxes are subjected to a wax decolorization process commonly referred to as a wax finish. Such methods are part of a time consuming and expensive process and also have a detrimental effect on opacity, which is a desirable property in various applications where good thermal and light properties, UV stability, color and storage stability are desired. give. Such applications include, but are not limited to, coating materials, crayons, markers, cosmetics, candles, electrical insulators, food and drug applications and the like.

Waxes prepared by hydrogenation of carbon monoxide by the Fischer-Tropsch process have many desirable properties, which are in many respects superior to petroleum waxes. They are high in paraffin content and are substantially free of the sulfur, nitrogen and aromatic impurities found in petroleum waxes.
However, untreated Fischer-Tropsch wax may contain small amounts of olefins and oxygenates (eg, long chain primary alcohols, acids and esters), which in some environments cause corrosion. there is a possibility. Therefore, Fischer-Tropsch wax is generally subjected to some hydrotreating to obtain high purity.

Furthermore, Fischer-Tropsch wax is harder than conventional petroleum wax. The hardness of waxes and wax blends, as measured by penetration, varies considerably. Wax hardness is generally measured by the penetration test of ASTM D 1321. It is generally advantageous for Fischer-Tropsch waxes to be hard because of the shortage of high grade hard paraffin wax. However, its hardness can limit the usefulness of untreated Fischer-Tropsch wax in certain applications. Therefore, it is desirable to provide a process by which the hardness of these waxes can be efficiently adjusted within the desired range during hydrotreating.

SUMMARY OF THE INVENTION The present invention removes any oxygenates, olefins and aromatic species that may be present from a Fischer-Tropsch feedstock wax while at the same time reducing its hardness, thereby limiting the need for further processing. Or a mild hydrotreating method to eliminate.

This process produces a Fischer-Tropsch feedstock wax in a hydrocarbon synthesis process, which is then passed over a hydroisomerization catalyst under mild conditions to effect a boiling point conversion (hydrocracking) of 10%. %, While undergoing chemical conversions (eg, hydrogenation and mild isomerization), by which
The overall yield of isomerized wax is retained.

In one embodiment of the present invention, the Fischer-Tropsch feedstock wax is compounded by hydrocarbon synthesis and comprises ASTM Standard Test Meth.
The wax hardness, defined by the wax penetration (ASTM D-1321), is adjusted within the preferred range for end use and at the same time, if present, e.g. oxygenates (e.g. primary alcohols), Remove unwanted impurities such as olefins and trace levels of aromatics.

DETAILED DESCRIPTION OF THE INVENTION The Fischer-Tropsch process can produce a variety of materials depending on the catalyst and process conditions. The waxy products of hydrocarbon synthesis processes, especially those from cobalt-based catalytic processes, contain a high proportion of normal paraffins. Cobalt is the preferred Fischer-Tropsch catalytic metal in that it is desirable for the purposes of the present invention to start with a Fischer-Tropsch wax product having a high proportion of high molecular weight chain _{C20 +} paraffins.

The preferred Fischer-Tropsch reactor for producing the raw wax of the present invention is a slurry foam column reactor. This reactor is ideal for carrying out highly exothermic three-phase catalytic reactions. In such a reactor (which may include catalyst regeneration / recirculation means as shown in U.S. Pat. No. 5,260,239), a solid phase catalyst is provided by a gas phase which continuously foams through the liquid phase. At least partially in the liquid phase,
It is held in dispersion or suspension, which results in a slurry. The catalyst used in such a reactor can be either a bulk catalyst or any supported catalyst.

The catalyst in the slurry phase Fischer-Tropsch reaction useful in the present invention is preferably a cobalt, more preferably a cobalt-rhenium catalyst. The reaction is carried out at pressures and temperatures typical in a Fischer-Tropsch process, ie temperatures of about 190 ° C to about 235 ° C, preferably about 195 ° C to about 225 ° C. The raw material is, for example, at least about 12 cm / sec, preferably about 12 cm
/ Sec to about 23 cm / sec is introduced at a linear velocity. For a preferred process of operating a slurry phase Fischer-Tropsch reactor, see US Pat. No. 5,348,98.
No. 2 is described.

A preferred Fischer-Tropsch process is one that uses a non-shifting (ie, incapable of undergoing a water gas shift reaction) catalyst. Non shifting Fischer - Tropsch reactions are well known to those skilled in the art, it has a feature that conditions for the formation of by-product CO ₂ to a minimum. As the non-shifting catalyst, for example, cobalt,
Mention may be made of ruthenium or mixtures thereof, preferably cobalt, more preferably supported-promoted cobalt in which the promoter is zirconium or rhenium, preferably rhenium. Such catalysts are well known and the preferred catalyst is U.S. Pat. No. 4,568,6.
63 and EP 0 266 898.

By using the Fischer-Tropsch process, a boiling range of 371 ° C. +
The recovered C ₂₀₊ waxy hydrocarbons are free of sulfur and nitrogen.
These heteroatom compounds are poisons for Fischer-Tropsch catalysts and are removed from the methane-containing natural gas normally used to make synthesis gas feed for Fischer-Tropsch processes. In the Fischer-Tropsch process, small amounts of olefins are produced with oxygenated compounds such as alcohols and acids.

The raw wax product of the Fischer-Tropsch synthesis is subjected to a mild hydroisomerization process. The entire liquid distillate of the synthesis process may be withdrawn from the reactor and sent directly to the hydroisomerization stage. In other embodiments, unconverted hydrogen and carbon monoxide, and water formed during the synthesis may be removed prior to the hydroisomerization step. If desired, lower molecular weight products of the synthesis stage, in particular C ₄ -fractions, such as methane, ethane and propane, may also be removed before the hydroisomerization process. Separation is conveniently carried out using distillation techniques well known in the art. In another embodiment, wax fractions typically boiling above 371 ° C at atmospheric pressure are separated from the Fischer-Tropsch process hydrocarbon product and subjected to the hydroisomerization process of the present invention.

Hydroisomerization is a well-known process, the conditions of which can vary widely. One factor to note in the hydroisomerization process is that of the feedstock hydrocarbons with boiling points above 371 ° C,
Increasing conversion to hydrocarbons with boiling points below 371 ° C. tends to increase cracking, resulting in higher gas and other distillate yields and lower isomerized wax yields. In the present invention, decomposition is kept to a minimum, usually less than 10%, preferably less than 5%, more preferably less than 1% to maximize wax yield.

The hydroisomerization step is such that the conversion of a substance having a boiling point of 371 ° C. + to a substance having a boiling point of 371 ° C.− is less than about 10%, more preferably less than about 5%, most preferably less than about 1%. Under various conditions in the presence of hydrogen with a hydroisomerization catalyst. These conditions include a temperature of about 204 ° C to about 343 ° C, preferably about 286 ° C to about 321 ° C.
Hydrogen pressure is about 300 to about 1500 psig, preferably about 500 to about 1000 p.
sig, more preferably about 700 to about 900 psig, which is a relatively mild condition. These are to reduce oxygenate and trace olefin levels in the Fischer-Tropsch wax and partially isomerize the wax.

Typical broad and preferred conditions for the hydroisomerization process of the present invention are summarized in the table below.

[0020]       conditions                      Wide range                  Narrow range Temperature, ° C 204-343 286-321 Total pressure, psig 300-1500 500-1000 Hydrogen treatment ratio, SCF / B 500-5000 2000-4000

The resulting hydrotreated / hydroisomerized Fischer-Tropsch wax is then fractionated to give a wax fraction having the desired melting point (or boiling point) and penetration.

Virtually all useful catalysts for hydroisomerization are satisfactory in mild hydrotreating / hydroisomerization processes, although some catalysts work better than others and are preferred. For example, a supported catalyst containing a Group VIII noble metal, such as platinum or palladium, contains one or more Group VIII base metals, such as nickel or cobalt, at about 0.
It is particularly useful, as are catalysts that contain 5 to 20 wt% and may or may not contain Group VI metals such as molybdenum in amounts of about 1 to 20 wt%. Any refractory oxide, zeolite or mixtures thereof can be used as the metal support. Preferred carriers include silica, alumina, silica-alumina, silica-alumina phosphate, titania, zirconia, vanadia and other Group III, IV, VA or VI oxides, and Y-sheaves such as ultra-stable Y-sieves. . Preferred carriers include alumina, silica-alumina having a bulk carrier silica concentration of less than about 50 wt%, preferably less than about 35 wt%. A more preferred carrier is less than about 20 wt% silica, preferably about 10 wt.
Amorphous silica-alumina co-gels present in an amount of ˜20 wt%. The carrier may also contain small amounts, ie 20 to 30 wt% of binders such as alumina, silica, Group IVA metal oxides and various clays, magnesia, etc., preferably alumina.

Preferred catalysts in the present invention include catalysts supported on an acidic support that include a non-noble metal Group VIII metal, eg cobalt, with a Group VI metal, eg molybdenum. The surface area of the preferred catalyst is about 180-400 m ² / gm, preferably 230-350 m ² / gm, the pore volume is 0.3-1.0 ml / gm, preferably 0.35-0.75 ml / gm, bulk density Is about 0.5 to 1.0 g / ml, and the side crushing strength is about 0.8 to 3.5 kg / mm.

Preferred catalysts are prepared by co-impregnating a solution from the metal on a support, drying at 100-150 ° C. and calcining in air at 200-550 ° C. For the preparation of carrier amorphous microspherical silica-alumina, see Ryland, Lloyd B .;
, Tamele, M .; W. And Wilson, J .; N. , Cracking
Catalysts (Catalysts, Volume VII, Paul H. Emm
ett ed., Rainhold Publishing Corporation, New York, 1960, pp. 5-9).

In a preferred catalyst, the Group VIII metal is less than about 5 wt%, preferably 2-3.
wt%, while the Group VI metal is usually present in higher amounts, eg 10-2.
Present in an amount of 0 wt%. A typical catalyst is shown below.

Co wt% 2.5-3.5 Mo wt% 15-20 Al ₂ O ₃ -SiO ₂ 60-70 Al ₂ O ₃ -Binder 2-25 Surface area 290-355 m ² / gm Pore volume (Hg ) 0.35-0.45 ml / gm Bulk density 0.58-0.68 g / ml

Referring to FIG. 1, synthesis gas (proper proportions of hydrogen and carbon monoxide) is fed to a Fischer-Tropsch reactor 1, preferably a slurry reactor, in which it contacts a proper Fischer-Tropsch catalyst. Let Fischer-Tropsch (F /
T) The raw wax product is recovered directly from reactor 1. At least a part of this Fischer-Tropsch raw material wax is introduced into the hydroisomerization process unit 2 together with hydrogen and brought into contact with the hydroisomerization catalyst under mild hydroisomerization conditions. If desired, the isomerized Fischer-Tropsch (F / T) wax from the hydroisomerization zone of hydroisomerization process unit 2 is fractionally distilled in separation zone 3 under vacuum,
It may be the final wax fraction product of various melting points.

The following examples are used to illustrate the present invention without however limiting it.

Example 1-Preparation of Fischer-Tropsch Wax A mixture of hydrogen and carbon monoxide syngas (H ₂ /CO=2.0-2.2) was added to heavy paraffin in a slurry foam column Fischer-Tropsch reactor. Was converted to. The catalyst used was the titania supported cobalt-rhenium catalyst described in the aforementioned US Pat. No. 4,568,663. The reaction is about 204-232 ° C, 280 psig
The raw material was introduced at a linear velocity of 12 to 17.5 cm / sec. Fisher-
The dynamic alpha of the Tropsch product was 0.90 to 0.96. The Fischer-Tropsch wax product was withdrawn directly from the slurry reactor.

Example 2-Hydrogenated / Hydroisomerized Fischer-Tropsch Raw Wax The Fischer-Tropsch wax prepared in Example 1 was subjected to silica- Treated over an alumina supported cobalt-molybdenum catalyst. The hydrotreated / hydroisomerized Fischer-Tropsch wax was then fractionally distilled under vacuum. For each of these runs (designated as Levels A-E), the conditions and conversions of fractions boiling above 371 ° C and product yields relative to the untreated Fischer-Tropsch feed wax are shown in Table 1.

[0031]

[Table 1]

Example 3-Hydrogenation / Hydroisomerization Fischer-Tropsch Wax Melting Point and Penetration The melting point (mp ° C.) defined by the wax penetration according to the ASTM Standard Test Method (ASTM D-1321). And penetration was measured for each fraction. The penetration of wax is
The depth of penetration of a standard needle into the wax is expressed in units of 1/10 (dmm) of millimeter. Penetration is measured with a penetrometer in which a standard needle is applied to the sample for 5 seconds with a load of 100 grams.

[0033]

[Table 2]

From the data summarized in Tables 1 and 2 herein, it is shown that the present invention purifies Fischer-Tropsch wax while at the same time adjusting the hardness and melting point of the refined wax to within the desired ranges. It is clear that it teaches possible alternative processes.

The present invention also relates to the waxes described herein. In particular, the invention also relates to a treated Fischer-Tropsch wax having a penetration of up to 50% higher than the same untreated Fischer-Tropsch wax. Such treated wax has a melting point difference of less than about 5 ° C with the same untreated Fischer-Tropsch wax.

Many modifications and alternative embodiments of the invention will be apparent to those skilled in the art from the foregoing description. Therefore, this description is to be considered exemplary only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of this process may vary substantially without departing from the spirit of the invention,
The exclusive use of any modification that comes within the scope of the appended claims is reserved.

[Brief description of drawings]

[Figure 1]   1 shows a schematic diagram of a process according to the invention.

[Explanation of symbols]

  1: Fischer-Tropsch reactor   2: Hydroisomerization process unit   3: Separation area

─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Riley, Daniel, Francis             70820, Louisiana, United States               Baton Rouge, Gabriel Oak             Sdrive 6211 F-term (reference) 4H029 CA00 DA00 DA11 DA14

Claims (19)

[Claims] 1. A method of forming a hydrocarbon wax product from syngas, comprising: a) reacting the syngas in the presence of a Fischer-Tropsch catalyst under Fischer-Tropsch reaction conditions to provide a first penetration index. And Fischer-Tropsch feedstock wax having a first melting point; and b) in the hydroisomerization zone, in the presence of a hydroisomerization catalyst, the Fischer-Tropsch feedstock wax and hydrogen under hydroisomerization conditions. And the conversion rate of the fraction having a boiling point of 371 ° C. + to the fraction having a boiling point of 371 ° C.− in the hydroisomerization region is 1
A method of forming a hydrocarbon wax product comprising hydroisomerizing the wax to less than 0% to form an isomerized Fischer-Tropsch wax having a second penetration and a second melting point. . 2. The second melting point is 0 to 5 ° C. lower than the first melting point, and the second penetration is 0 to 50% higher than the first penetration. A method of forming the hydrocarbon wax product of claim 1, wherein the method comprises: 3. The method according to claim 1, wherein the hydroisomerization catalyst used in step (b) is supported on an acidic support and contains a Group VI metal and a Group VIII non-noble metal. A method of forming a hydrocarbon wax product. 4. The method according to claim 2, wherein the hydroisomerization catalyst used in step (b) is supported on an acidic carrier and contains a Group VI metal and a Group VIII non-noble metal. A method of forming a hydrocarbon wax product. 5. The group VIII metal of the hydroisomerization catalyst used in step (b) is cobalt, the group VI metal is molybdenum, and the carrier is silica-alumina. Process according to claim 3, characterized in that the Fischer-Tropsch catalyst used in)) comprises cobalt, ruthenium or a mixture thereof. 6. The group VIII metal of the hydroisomerization catalyst used in step (b) is cobalt, the group VI metal is molybdenum, and the support is silica-alumina. Process according to claim 4, characterized in that the Fischer-Tropsch catalyst used in) comprises cobalt, ruthenium or a mixture thereof. 7. The hydroisomerization catalyst comprises 1-5 wt% cobalt and 10-2.
A process for forming a hydrocarbon wax product according to claim 1, characterized in that it comprises 0% by weight of molybdenum. 8. The hydroisomerization catalyst comprises 1-5 wt% cobalt and 10-2.
Process for forming a hydrocarbon wax product according to claim 2, characterized in that it comprises 0% by weight of molybdenum. 9. The method of claim 1, wherein the mild hydrotreating / hydroisomerizing conditions in step (b) include a temperature of 204 ° C. to 343 ° C. and a hydrogen pressure of 700 to 750 psig. A method of forming the described hydrocarbon wax product. 10. The mild hydroisomerization condition in step (b) is 286.
Process for forming a hydrocarbon wax product according to claim 9, characterized in that it comprises a temperature of between 0 ° C and 321 ° C. 11. The boiling point 3 of the fraction having a boiling point of 371 ° C. + in the hydroisomerization region.
Process for forming a hydrocarbon wax product according to claim 1, characterized in that the conversion to 71 ° C-fraction is less than 5%. 12. The boiling point 3 of the fraction having a boiling point of 371 ° C. + in the hydroisomerization region.
Process for forming a hydrocarbon wax product according to claim 2, characterized in that the conversion to 71 ° C-fraction is less than 5%. 13. The boiling point 3 of the fraction having a boiling point of 371 ° C. + in the hydroisomerization region.
Process for forming a hydrocarbon wax product according to claim 11, characterized in that the conversion to 71 ° C-fraction is less than 1%. 14. The method for forming a hydrocarbon wax product of claim 1, wherein the Fischer-Tropsch reaction is carried out under non-shifting conditions. 15. The method of forming a hydrocarbon wax product of claim 1, wherein the Fischer-Tropsch reactor is a slurry foam column reactor. 16. A hydrocarbon wax product comprising a wax produced by the method of claim 1. 17. A hydrocarbon wax product comprising a wax produced by the method of claim 2. 18. A hydrocarbon wax product comprising a hydroisomerized wax having a penetration of up to 50% greater than the same untreated wax and having a melting point difference within 5 ° C. with the same untreated wax. . 19. A hydrocarbon wax product formed by the method of claim 5.